Studies on Cetane Number and Lubricity of Additives from Vegetable Oils

Abstract

The present work envisaged to synthesize, characterize and evaluate the dual functional diesel additives from the vegetable oils using heterogeneous catalyst. Mainly three different types of solid catalysts have been prepared viz., Li/CaO, Ni/CaO and Ti/SiO2 and characterized by various spectroscopic and analytical techniques (powder XRD, BET surface area, FESEM, TEM and Hammett indicator studies). The Li/CaO has been used for the transesterification of a variety of triglycerides viz., used cotton seed, soybean, jatropha, castor, karanja oil and mutton fat. The prepared fatty acid methyl esters (FAMEs) of cotton seed, jatropha and karanja oil have been used as substrate for the aminolysis reaction with diethanolamine in order to prepare the fatty acid amide derivatives using Ni/CaO as solid catalyst. The resulted amide derivatives being having long hydrocarbon chain and amide group, are expected to improve the lubricity as well as cetane number of the diesel fuel. The vegetable oil derived fatty acid esters have unsaturation (- CH=CH-) in hydrocarbon chain and in order to prepare lubricity improvers for high temperature applications the -CH=CH- have been epoxidized using Ti/SiO2 as solid catalyst. All the prepared catalysts have also been reused successfully several times. The fatty acid methyl esters derived from castor oil has –OH group at C-12 position, and same has been nitrated with the help of nitric acid and acetic anhydride. All vegetable oil derivatives have been well characterized by FT-IR, proton NMR and in few cases mass spectroscopic studies. Finally the nitrate derivative of castor oil derived FAMEs and amide derivative of used cotton seed oil were tested as dual functional diesel fuel additives and their cetane number and lubricity improver properties has been evaluated. The nitrate derivative was found to improve the cetane number of the base diesel fuel from 52.4 to 56.0 and lubricity from 458 to 152 μm. While, the amide derivative was found to improve the cetane number of the base diesel fuel from 52.4 to 56.0 and lubricity from 458 to 143 μm. The epoxidized derivative of used cotton seed oil derived FAMEs has been evaluated as lubricity improver only, and found to improve the lubricity of base diesel fuel from 458 to 115 μm.